Antennas are mounted on a variety of platforms to perform a variety of functions. For example, antennas are oftentimes mounted on the surface of an airplane and other air vehicle, such as a missile or a helicopter, to provide, among other functions, direction finding and communications-related functions. Due to size limitations of many mounting platforms, the size of the antenna is preferably minimized.
In addition, for antennas mounted on airplanes, the amount by which the antenna protrudes beyond the surface or skin of the aircraft is also preferably minimized so as to thereby reduce the effect of an antenna on the radar signature of the aircraft. In order to reduce the amount by which a conventional antenna extends or protrudes beyond the surface of a mounting platform, such as the surface of an airplane, conventional antennas are generally mounted in a cavity defined within the surface of the aircraft. In addition, conventional planar microstrip antennas may also be mounted in a lossy cavity in order to absorb radiation on one side of the planar antenna, thereby providing a microstrip antenna having a unidirectional pattern.
Thus, while the radiating element may only protrude slightly beyond the surface of the aircraft, a sizable cavity is oftentimes required below the surface to provide adequate antenna radiation and reception performance. In order to provide a sufficiently large cavity in which to mount the antenna, the load bearing structure of the platform, such as the aircraft, must generally be relocated or other load bearing structures must be enlarged in order to compensate for the lack of structural support within the cavity.
It is also desirable in many instances to mount an antenna on a platform which is not flat or planar, but which has a complex shape. For example, it is oftentimes desirable to mount an antenna on the leading edge of an aircraft wing, the trailing edge of an aircraft wing or the tail of an aircraft in order to optimize the performance of the antenna. However, conventional antennas are difficult to shape into the desired complex shape while maintaining the proper performance characteristics.